fix: add contents:write permission to release job to fix 403 error

The release job was failing with 'Error 403: Resource not accessible by integration'
because it lacked permissions to create releases and generate release notes.

This adds the required 'contents: write' permission to allow the ncipollo/release-action
to successfully create GitHub releases and generate release notes via the API.

Author: clemensv

.github/workflows/main-ci-build.yml

@@ -117,6 +117,8 @@ jobs:
     needs: build
     runs-on: ubuntu-latest
     if: startsWith(github.ref, 'refs/tags/v')
+    permissions:
+      contents: write
     steps:
       - name: Download all artifacts
         uses: actions/download-artifact@v4